He built it – and they came. The hall in question was the Pearse-Connolly Hall, put up in the 1920s in County Leitrim by the charismatic Irish communist leader Jimmy Gralton. (It is named after Patrick Pearse and James Connolly, executed leaders of the 1916 Easter rising.) Gralton infuriated the leaders of Ireland's post-civil war church and state for daring to make his building a dance hall for raucous nights out, as well as a daytime venue for educational classes. Appallingly, people were encouraged to enjoy themselves there. Fun and secular thinking? What a double whammy. The tempestuous life and times of Jimmy and his hall are dramatised by screenwriter Paul Laverty and director Ken Loach; their story becomes a duel between the truculent, articulate Gralton, played by Barry Ward and a ferocious parish priest, played by Jim Norton – contemptuous of modernity and on a mission to destroy this antichrist of the left.

It is a watchable and thoughtful, if slightly pedagogic film, with some wonderful moments, presented with great clarity and seriousness, absolutely unflavoured by irony or cynicism. Laverty and Loach may have been influenced, just the tiniest bit, by John Ford's The Quiet Man (except their man is extremely noisy) and possibly a little by Warren Beatty's 1981 film Reds, about the American communist John C Reed, but it basically returns to the themes of their Palme d'Or winning 2006 film, The Wind That Shakes the Barley about the divisions in Ireland after the civil war: the frustration and rage felt by a younger progressive generation on realising that their new political masters could be just as reactionary and inward-looking as the Brits. Jimmy's Hall is a powerful film in many ways, though with a strange and prominent flaw: having painted him as Gralton's implacable foe, the movie suddenly gives the priest unconvincing and unmotivated sympathies with Gralton. After being so implacably opposed to everything Gralton stands for, the priest will periodically and bafflingly praise his integrity. Perhaps Paul Laverty, with all the magnanimity of being on history's winning side, can't bear to portray the priest in too horrible a light. But it is an odd piece of fence-sitting.

Barry Ward's Jimmy Gralton is a man who returns to his native Ireland in the early 1930s after a decade away in the United States; he's seen for himself the depression and the Wall Street ruin. His brother has just died and initially he has no plans other than helping his mother with the small family farm. But soon all the young kids – bored to tears with nothing to do thereabouts – are begging him to reopen the hall he built as a co-operative project with locals: more fun, more laughs, more leftwing thinking. Gralton astonishes everyone by producing a wind-up gramophone he's brought back from the States, with the latest jazz records, and teaches them some cheeky, sexy dancing – an entertainingly surreal moment. But reopening the hall reopens old wounds: a spark is rekindled with a woman (played by Simone Kirby) with whom he was once and is still in love, and it redraws the battle lines with the tough guys of the old IRA who are now part of an authoritarian political establishment. Jimmy's Hall is now a focus of discontent and an dangerous alternative power base.

The movie interestingly challenges accepted narratives about emigration from Ireland to the United States: America is not just a place for business opportunities but subversive political ideas which can be reimported into the old country. The republican warriors are not the heroes here. The IRA man O'Keeffe (Brian F O'Byrne) is a cruel, closed-minded bully. Ironically, it is the priest who challenges Gralton about the realities of Stalin's rule – evasively, Gralton says that it is a matter for later "debate" – but a further irony is that the priest only invokes Stalin with a view to enforcing his own rule.

The movie is at its best when it simply expounds an idealism, with its own distinctive frankness. There is a wonderful sequence in which people just sit in a circle in Jimmy's hall for a sort of practical criticism session: they discuss WB Yeats's poem The Song of the Wandering Aengus, and talk about what it means to them. I could watch simple, thoughtful scenes like this for hours on end.